The present invention relates to a micromechanical inertial sensor and to a method for manufacturing a micromechanical inertial sensor.
Micromechanical inertial sensors are used, for example, for measuring accelerations or rates of rotation. The technology of micromechanics allows such acceleration or rate-of-rotation sensors to be produced in a very small space and in a relatively inexpensive manner. In this context, structures are made, for example, from semiconductor components, which allow the measurement of accelerations based on inertial forces or also, for example, the measurement of rates of rotation based on the Coriolis effect.
Sensors of this type can be used in different technical areas, such as in vehicles or in the aviation sector. In motor vehicles, acceleration sensors are used, for example, to trigger air-bag systems. Another field of application is vehicle dymamics control systems, a central part of which is the measurement of the rate of rotation and acceleration in several spatial directions. In navigation applications, accurate measurement of a rate of rotation or acceleration is used to determine the position or path, in particular, as a complement to satellite navigation systems.
In the field of micromechanical inertial sensors, inexpensive solutions are of particular importance in order to allow mass production or use in large numbers. A further important factor is the accuracy of such sensors. Moreover, a small size is of central importance, in particular, for use in mobile systems, such as in land vehicles or aircraft, or also in the space flight applications.
U.S. Pat. No. 4,598,585 discloses a planar inertial sensor having a gimbal structure for measuring rates of rotation based on the Coriolis effect. The gimbal structure is formed in a thin layer of silicon dioxide. A part of the gimbal structure is set into oscillations by a driving element, and a deflection of the other part of the gimbal structure, which occurs during a rotary motion due to action of a Coriolis force, is measured by measuring elements.
An example of a micromechanical acceleration sensor is described in German Patent Application DE 44 39 238 A1. The capacitive acceleration sensor disclosed therein has a planar design and is composed of two semiconductor bodies that are connected to each other in a planar manner. A floating structure is connected to one of the semiconductor bodies and freely movable in a direction perpendicular to the surface of the two semiconductor bodies.